text: /*
   * Handle git attributes.  See gitattributes(5) for a description of
   * the file syntax, and attr.h for a description of the API.
   *
   * One basic design decision here is that we are not going to support
   * an insanely large number of attributes.
   */
  
  #include "cache.h"
  #include "config.h"
  #include "exec-cmd.h"
  #include "attr.h"
  #include "dir.h"
  #include "utf8.h"
  #include "quote.h"
  #include "thread-utils.h"
  
  const char git_attr__true[] = "(builtin)true";
  const char git_attr__false[] = "\0(builtin)false";
  static const char git_attr__unknown[] = "(builtin)unknown";
  #define ATTR__TRUE git_attr__true
  #define ATTR__FALSE git_attr__false
  #define ATTR__UNSET NULL
  #define ATTR__UNKNOWN git_attr__unknown
  
  #ifndef DEBUG_ATTR
  #define DEBUG_ATTR 0
  #endif
  
  struct git_attr {
  	int attr_nr; /* unique attribute number */
  	char name[FLEX_ARRAY]; /* attribute name */
  };
  
  const char *git_attr_name(const struct git_attr *attr)
  {
  	return attr->name;
  }
  
  struct attr_hashmap {
  	struct hashmap map;
  	pthread_mutex_t mutex;
  };
  
  static inline void hashmap_lock(struct attr_hashmap *map)
  {
  	pthread_mutex_lock(&map->mutex);
  }
  
  static inline void hashmap_unlock(struct attr_hashmap *map)
  {
  	pthread_mutex_unlock(&map->mutex);
  }
  
  /*
   * The global dictionary of all interned attributes.  This
   * is a singleton object which is shared between threads.
   * Access to this dictionary must be surrounded with a mutex.
   */
  static struct attr_hashmap g_attr_hashmap;
  
  /* The container for objects stored in "struct attr_hashmap" */
  struct attr_hash_entry {
  	struct hashmap_entry ent;
  	const char *key; /* the key; memory should be owned by value */
  	size_t keylen; /* length of the key */
  	void *value; /* the stored value */
  };
  
  /* attr_hashmap comparison function */
  static int attr_hash_entry_cmp(const void *unused_cmp_data,
  			       const struct hashmap_entry *eptr,
  			       const struct hashmap_entry *entry_or_key,
  			       const void *unused_keydata)
  {
  	const struct attr_hash_entry *a, *b;
  
  	a = container_of(eptr, const struct attr_hash_entry, ent);
  	b = container_of(entry_or_key, const struct attr_hash_entry, ent);
  	return (a->keylen != b->keylen) || strncmp(a->key, b->key, a->keylen);
  }
  
  /* Initialize an 'attr_hashmap' object */
  static void attr_hashmap_init(struct attr_hashmap *map)
  {
  	hashmap_init(&map->map, attr_hash_entry_cmp, NULL, 0);
  }
  
  /*
   * Retrieve the 'value' stored in a hashmap given the provided 'key'.
   * If there is no matching entry, return NULL.
   */
  static void *attr_hashmap_get(struct attr_hashmap *map,
  			      const char *key, size_t keylen)
  {
  	struct attr_hash_entry k;
  	struct attr_hash_entry *e;
  
  	if (!map->map.tablesize)
  		attr_hashmap_init(map);
  
  	hashmap_entry_init(&k.ent, memhash(key, keylen));
  	k.key = key;
  	k.keylen = keylen;
  	e = hashmap_get_entry(&map->map, &k, ent, NULL);
  
  	return e ? e->value : NULL;
  }
  
  /* Add 'value' to a hashmap based on the provided 'key'. */
  static void attr_hashmap_add(struct attr_hashmap *map,
  			     const char *key, size_t keylen,
  			     void *value)
  {
  	struct attr_hash_entry *e;
  
  	if (!map->map.tablesize)
  		attr_hashmap_init(map);
  
  	e = xmalloc(sizeof(struct attr_hash_entry));
  	hashmap_entry_init(&e->ent, memhash(key, keylen));
  	e->key = key;
  	e->keylen = keylen;
  	e->value = value;
  
  	hashmap_add(&map->map, &e->ent);
  }
  
  struct all_attrs_item {
  	const struct git_attr *attr;
  	const char *value;
  	/*
  	 * If 'macro' is non-NULL, indicates that 'attr' is a macro based on
  	 * the current attribute stack and contains a pointer to the match_attr
  	 * definition of the macro
  	 */
  	const struct match_attr *macro;
  };
  
  /*
   * Reallocate and reinitialize the array of all attributes (which is used in
   * the attribute collection process) in 'check' based on the global dictionary
   * of attributes.
   */
  static void all_attrs_init(struct attr_hashmap *map, struct attr_check *check)
  {
  	int i;
  	unsigned int size;
  
  	hashmap_lock(map);
  
  	size = hashmap_get_size(&map->map);
  	if (size < check->all_attrs_nr)
  		BUG("interned attributes shouldn't be deleted");
  
  	/*
  	 * If the number of attributes in the global dictionary has increased
  	 * (or this attr_check instance doesn't have an initialized all_attrs
  	 * field), reallocate the provided attr_check instance's all_attrs
  	 * field and fill each entry with its corresponding git_attr.
  	 */
  	if (size != check->all_attrs_nr) {
  		struct attr_hash_entry *e;
  		struct hashmap_iter iter;
  
  		REALLOC_ARRAY(check->all_attrs, size);
  		check->all_attrs_nr = size;
  
  		hashmap_for_each_entry(&map->map, &iter, e,
  					ent /* member name */) {
  			const struct git_attr *a = e->value;
  			check->all_attrs[a->attr_nr].attr = a;
  		}
  	}
  
  	hashmap_unlock(map);
  
  	/*
  	 * Re-initialize every entry in check->all_attrs.
  	 * This re-initialization can live outside of the locked region since
  	 * the attribute dictionary is no longer being accessed.
  	 */
  	for (i = 0; i < check->all_attrs_nr; i++) {
  		check->all_attrs[i].value = ATTR__UNKNOWN;
  		check->all_attrs[i].macro = NULL;
  	}
  }
  
  static int attr_name_valid(const char *name, size_t namelen)
  {
  	/*
  	 * Attribute name cannot begin with '-' and must consist of
  	 * characters from [-A-Za-z0-9_.].
  	 */
  	if (namelen <= 0 || *name == '-')
  		return 0;
  	while (namelen--) {
  		char ch = *name++;
  		if (! (ch == '-' || ch == '.' || ch == '_' ||
  		       ('0' <= ch && ch <= '9') ||
  		       ('a' <= ch && ch <= 'z') ||
  		       ('A' <= ch && ch <= 'Z')) )
  			return 0;
  	}
  	return 1;
  }
  
  static void report_invalid_attr(const char *name, size_t len,
  				const char *src, int lineno)
  {
  	struct strbuf err = STRBUF_INIT;
  	strbuf_addf(&err, _("%.*s is not a valid attribute name"),
  		    (int) len, name);
  	fprintf(stderr, "%s: %s:%d\n", err.buf, src, lineno);
  	strbuf_release(&err);
  }
  
  /*
   * Given a 'name', lookup and return the corresponding attribute in the global
   * dictionary.  If no entry is found, create a new attribute and store it in
   * the dictionary.
   */
  static const struct git_attr *git_attr_internal(const char *name, int namelen)
  {
  	struct git_attr *a;
  
  	if (!attr_name_valid(name, namelen))
  		return NULL;
  
  	hashmap_lock(&g_attr_hashmap);
  
  	a = attr_hashmap_get(&g_attr_hashmap, name, namelen);
  
  	if (!a) {
  		FLEX_ALLOC_MEM(a, name, name, namelen);
  		a->attr_nr = hashmap_get_size(&g_attr_hashmap.map);
  
  		attr_hashmap_add(&g_attr_hashmap, a->name, namelen, a);
  		assert(a->attr_nr ==
  		       (hashmap_get_size(&g_attr_hashmap.map) - 1));
  	}
  
  	hashmap_unlock(&g_attr_hashmap);
  
  	return a;
  }
  
  const struct git_attr *git_attr(const char *name)
  {
  	return git_attr_internal(name, strlen(name));
  }
  
  /* What does a matched pattern decide? */
  struct attr_state {
  	const struct git_attr *attr;
  	const char *setto;
  };
  
  struct pattern {
  	const char *pattern;
  	int patternlen;
  	int nowildcardlen;
  	unsigned flags;		/* PATTERN_FLAG_* */
  };
  
  /*
   * One rule, as from a .gitattributes file.
   *
   * If is_macro is true, then u.attr is a pointer to the git_attr being
   * defined.
   *
   * If is_macro is false, then u.pat is the filename pattern to which the
   * rule applies.
   *
   * In either case, num_attr is the number of attributes affected by
   * this rule, and state is an array listing them.  The attributes are
   * listed as they appear in the file (macros unexpanded).
   */
  struct match_attr {
  	union {
  		struct pattern pat;
  		const struct git_attr *attr;
  	} u;
  	char is_macro;
  	unsigned num_attr;
  	struct attr_state state[FLEX_ARRAY];
  };
  
  static const char blank[] = " \t\r\n";
  
  /*
   * Parse a whitespace-delimited attribute state (i.e., "attr",
   * "-attr", "!attr", or "attr=value") from the string starting at src.
   * If e is not NULL, write the results to *e.  Return a pointer to the
   * remainder of the string (with leading whitespace removed), or NULL
   * if there was an error.
   */
  static const char *parse_attr(const char *src, int lineno, const char *cp,
  			      struct attr_state *e)
  {
  	const char *ep, *equals;
  	int len;
  
  	ep = cp + strcspn(cp, blank);
  	equals = strchr(cp, '=');
  	if (equals && ep < equals)
  		equals = NULL;
  	if (equals)
  		len = equals - cp;
  	else
  		len = ep - cp;
  	if (!e) {
  		if (*cp == '-' || *cp == '!') {
  			cp++;
  			len--;
  		}
  		if (!attr_name_valid(cp, len)) {
  			report_invalid_attr(cp, len, src, lineno);
  			return NULL;
  		}
  	} else {
  		/*
  		 * As this function is always called twice, once with
  		 * e == NULL in the first pass and then e != NULL in
  		 * the second pass, no need for attr_name_valid()
  		 * check here.
  		 */
  		if (*cp == '-' || *cp == '!') {
  			e->setto = (*cp == '-') ? ATTR__FALSE : ATTR__UNSET;
  			cp++;
  			len--;
  		}
  		else if (!equals)
  			e->setto = ATTR__TRUE;
  		else {
  			e->setto = xmemdupz(equals + 1, ep - equals - 1);
  		}
  		e->attr = git_attr_internal(cp, len);
  	}
  	return ep + strspn(ep, blank);
  }
  
  static struct match_attr *parse_attr_line(const char *line, const char *src,
  					  int lineno, int macro_ok)
  {
  	int namelen;
  	int num_attr, i;
  	const char *cp, *name, *states;
  	struct match_attr *res = NULL;
  	int is_macro;
  	struct strbuf pattern = STRBUF_INIT;
  
  	cp = line + strspn(line, blank);
  	if (!*cp || *cp == '#')
  		return NULL;
  	name = cp;
  
  	if (*cp == '"' && !unquote_c_style(&pattern, name, &states)) {
  		name = pattern.buf;
  		namelen = pattern.len;
  	} else {
  		namelen = strcspn(name, blank);
  		states = name + namelen;
  	}
  
  	if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
  	    starts_with(name, ATTRIBUTE_MACRO_PREFIX)) {
  		if (!macro_ok) {
  			fprintf_ln(stderr, _("%s not allowed: %s:%d"),
  				   name, src, lineno);
  			goto fail_return;
  		}
  		is_macro = 1;
  		name += strlen(ATTRIBUTE_MACRO_PREFIX);
  		name += strspn(name, blank);
  		namelen = strcspn(name, blank);
  		if (!attr_name_valid(name, namelen)) {
  			report_invalid_attr(name, namelen, src, lineno);
  			goto fail_return;
  		}
  	}
  	else
  		is_macro = 0;
  
  	states += strspn(states, blank);
  
  	/* First pass to count the attr_states */
  	for (cp = states, num_attr = 0; *cp; num_attr++) {
  		cp = parse_attr(src, lineno, cp, NULL);
  		if (!cp)
  			goto fail_return;
  	}
  
  	res = xcalloc(1,
  		      sizeof(*res) +
  		      sizeof(struct attr_state) * num_attr +
  		      (is_macro ? 0 : namelen + 1));
  	if (is_macro) {
  		res->u.attr = git_attr_internal(name, namelen);
  	} else {
  		char *p = (char *)&(res->state[num_attr]);
  		memcpy(p, name, namelen);
  		res->u.pat.pattern = p;
  		parse_path_pattern(&res->u.pat.pattern,
  				      &res->u.pat.patternlen,
  				      &res->u.pat.flags,
  				      &res->u.pat.nowildcardlen);
  		if (res->u.pat.flags & PATTERN_FLAG_NEGATIVE) {
  			warning(_("Negative patterns are ignored in git attributes\n"
  				  "Use '\\!' for literal leading exclamation."));
  			goto fail_return;
  		}
  	}
  	res->is_macro = is_macro;
  	res->num_attr = num_attr;
  
  	/* Second pass to fill the attr_states */
  	for (cp = states, i = 0; *cp; i++) {
  		cp = parse_attr(src, lineno, cp, &(res->state[i]));
  	}
  
  	strbuf_release(&pattern);
  	return res;
  
  fail_return:
  	strbuf_release(&pattern);
  	free(res);
  	return NULL;
  }
  
  /*
   * Like info/exclude and .gitignore, the attribute information can
   * come from many places.
   *
   * (1) .gitattributes file of the same directory;
   * (2) .gitattributes file of the parent directory if (1) does not have
   *      any match; this goes recursively upwards, just like .gitignore.
   * (3) $GIT_DIR/info/attributes, which overrides both of the above.
   *
   * In the same file, later entries override the earlier match, so in the
   * global list, we would have entries from info/attributes the earliest
   * (reading the file from top to bottom), .gitattributes of the root
   * directory (again, reading the file from top to bottom) down to the
   * current directory, and then scan the list backwards to find the first match.
   * This is exactly the same as what is_excluded() does in dir.c to deal with
   * .gitignore file and info/excludes file as a fallback.
   */
  
  struct attr_stack {
  	struct attr_stack *prev;
  	char *origin;
  	size_t originlen;
  	unsigned num_matches;
  	unsigned alloc;
  	struct match_attr **attrs;
  };
  
  static void attr_stack_free(struct attr_stack *e)
  {
  	int i;
  	free(e->origin);
  	for (i = 0; i < e->num_matches; i++) {
  		struct match_attr *a = e->attrs[i];
  		int j;
  		for (j = 0; j < a->num_attr; j++) {
  			const char *setto = a->state[j].setto;
  			if (setto == ATTR__TRUE ||
  			    setto == ATTR__FALSE ||
  			    setto == ATTR__UNSET ||
  			    setto == ATTR__UNKNOWN)
  				;
  			else
  				free((char *) setto);
  		}
  		free(a);
  	}
  	free(e->attrs);
  	free(e);
  }
  
  static void drop_attr_stack(struct attr_stack **stack)
  {
  	while (*stack) {
  		struct attr_stack *elem = *stack;
  		*stack = elem->prev;
  		attr_stack_free(elem);
  	}
  }
  
  /* List of all attr_check structs; access should be surrounded by mutex */
  static struct check_vector {
  	size_t nr;
  	size_t alloc;
  	struct attr_check **checks;
  	pthread_mutex_t mutex;
  } check_vector;
  
  static inline void vector_lock(void)
  {
  	pthread_mutex_lock(&check_vector.mutex);
  }
  
  static inline void vector_unlock(void)
  {
  	pthread_mutex_unlock(&check_vector.mutex);
  }
  
  static void check_vector_add(struct attr_check *c)
  {
  	vector_lock();
  
  	ALLOC_GROW(check_vector.checks,
  		   check_vector.nr + 1,
  		   check_vector.alloc);
  	check_vector.checks[check_vector.nr++] = c;
  
  	vector_unlock();
  }
  
  static void check_vector_remove(struct attr_check *check)
  {
  	int i;
  
  	vector_lock();
  
  	/* Find entry */
  	for (i = 0; i < check_vector.nr; i++)
  		if (check_vector.checks[i] == check)
  			break;
  
  	if (i >= check_vector.nr)
  		BUG("no entry found");
  
  	/* shift entries over */
  	for (; i < check_vector.nr - 1; i++)
  		check_vector.checks[i] = check_vector.checks[i + 1];
  
  	check_vector.nr--;
  
  	vector_unlock();
  }
  
  /* Iterate through all attr_check instances and drop their stacks */
  static void drop_all_attr_stacks(void)
  {
  	int i;
  
  	vector_lock();
  
  	for (i = 0; i < check_vector.nr; i++) {
  		drop_attr_stack(&check_vector.checks[i]->stack);
  	}
  
  	vector_unlock();
  }
  
  struct attr_check *attr_check_alloc(void)
  {
  	struct attr_check *c = xcalloc(1, sizeof(struct attr_check));
  
  	/* save pointer to the check struct */
  	check_vector_add(c);
  
  	return c;
  }
  
  struct attr_check *attr_check_initl(const char *one, ...)
  {
  	struct attr_check *check;
  	int cnt;
  	va_list params;
  	const char *param;
  
  	va_start(params, one);
  	for (cnt = 1; (param = va_arg(params, const char *)) != NULL; cnt++)
  		;
  	va_end(params);
  
  	check = attr_check_alloc();
  	check->nr = cnt;
  	check->alloc = cnt;
  	check->items = xcalloc(cnt, sizeof(struct attr_check_item));
  
  	check->items[0].attr = git_attr(one);
  	va_start(params, one);
  	for (cnt = 1; cnt < check->nr; cnt++) {
  		const struct git_attr *attr;
  		param = va_arg(params, const char *);
  		if (!param)
  			BUG("counted %d != ended at %d",
  			    check->nr, cnt);
  		attr = git_attr(param);
  		if (!attr)
  			BUG("%s: not a valid attribute name", param);
  		check->items[cnt].attr = attr;
  	}
  	va_end(params);
  	return check;
  }
  
  struct attr_check *attr_check_dup(const struct attr_check *check)
  {
  	struct attr_check *ret;
  
  	if (!check)
  		return NULL;
  
  	ret = attr_check_alloc();
  
  	ret->nr = check->nr;
  	ret->alloc = check->alloc;
  	ALLOC_ARRAY(ret->items, ret->nr);
  	COPY_ARRAY(ret->items, check->items, ret->nr);
  
  	return ret;
  }
  
  struct attr_check_item *attr_check_append(struct attr_check *check,
  					  const struct git_attr *attr)
  {
  	struct attr_check_item *item;
  
  	ALLOC_GROW(check->items, check->nr + 1, check->alloc);
  	item = &check->items[check->nr++];
  	item->attr = attr;
  	return item;
  }
  
  void attr_check_reset(struct attr_check *check)
  {
  	check->nr = 0;
  }
  
  void attr_check_clear(struct attr_check *check)
  {
  	FREE_AND_NULL(check->items);
  	check->alloc = 0;
  	check->nr = 0;
  
  	FREE_AND_NULL(check->all_attrs);
  	check->all_attrs_nr = 0;
  
  	drop_attr_stack(&check->stack);
  }
  
  void attr_check_free(struct attr_check *check)
  {
  	if (check) {
  		/* Remove check from the check vector */
  		check_vector_remove(check);
  
  		attr_check_clear(check);
  		free(check);
  	}
  }
  
  static const char *builtin_attr[] = {
  	"[attr]binary -diff -merge -text",
  	NULL,
  };
  
  static void handle_attr_line(struct attr_stack *res,
  			     const char *line,
  			     const char *src,
  			     int lineno,
  			     int macro_ok)
  {
  	struct match_attr *a;
  
  	a = parse_attr_line(line, src, lineno, macro_ok);
  	if (!a)
  		return;
  	ALLOC_GROW(res->attrs, res->num_matches + 1, res->alloc);
  	res->attrs[res->num_matches++] = a;
  }
  
  static struct attr_stack *read_attr_from_array(const char **list)
  {
  	struct attr_stack *res;
  	const char *line;
  	int lineno = 0;
  
  	res = xcalloc(1, sizeof(*res));
  	while ((line = *(list++)) != NULL)
  		handle_attr_line(res, line, "[builtin]", ++lineno, 1);
  	return res;
  }
  
  /*
   * Callers into the attribute system assume there is a single, system-wide
   * global state where attributes are read from and when the state is flipped by
   * calling git_attr_set_direction(), the stack frames that have been
   * constructed need to be discarded so so that subsequent calls into the
   * attribute system will lazily read from the right place.  Since changing
   * direction causes a global paradigm shift, it should not ever be called while
   * another thread could potentially be calling into the attribute system.
   */
  static enum git_attr_direction direction;
  
  void git_attr_set_direction(enum git_attr_direction new_direction)
  {
  	if (is_bare_repository() && new_direction != GIT_ATTR_INDEX)
  		BUG("non-INDEX attr direction in a bare repo");
  
  	if (new_direction != direction)
  		drop_all_attr_stacks();
  
  	direction = new_direction;
  }
  
  static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
  {
  	FILE *fp = fopen_or_warn(path, "r");
  	struct attr_stack *res;
  	char buf[2048];
  	int lineno = 0;
  
  	if (!fp)
  		return NULL;
  	res = xcalloc(1, sizeof(*res));
  	while (fgets(buf, sizeof(buf), fp)) {
  		char *bufp = buf;
  		if (!lineno)
  			skip_utf8_bom(&bufp, strlen(bufp));
  		handle_attr_line(res, bufp, path, ++lineno, macro_ok);
  	}
  	fclose(fp);
  	return res;
  }
  
  static struct attr_stack *read_attr_from_index(const struct index_state *istate,
  					       const char *path,
  					       int macro_ok)
  {
  	struct attr_stack *res;
  	char *buf, *sp;
  	int lineno = 0;
  
  	if (!istate)
  		return NULL;
  
  	buf = read_blob_data_from_index(istate, path, NULL);
  	if (!buf)
  		return NULL;
  
  	res = xcalloc(1, sizeof(*res));
  	for (sp = buf; *sp; ) {
  		char *ep;
  		int more;
  
  		ep = strchrnul(sp, '\n');
  		more = (*ep == '\n');
  		*ep = '\0';
  		handle_attr_line(res, sp, path, ++lineno, macro_ok);
  		sp = ep + more;
  	}
  	free(buf);
  	return res;
  }
  
  static struct attr_stack *read_attr(const struct index_state *istate,
  				    const char *path, int macro_ok)
  {
  	struct attr_stack *res = NULL;
  
  	if (direction == GIT_ATTR_INDEX) {
  		res = read_attr_from_index(istate, path, macro_ok);
  	} else if (!is_bare_repository()) {
  		if (direction == GIT_ATTR_CHECKOUT) {
  			res = read_attr_from_index(istate, path, macro_ok);
  			if (!res)
  				res = read_attr_from_file(path, macro_ok);
  		} else if (direction == GIT_ATTR_CHECKIN) {
  			res = read_attr_from_file(path, macro_ok);
  			if (!res)
  				/*
  				 * There is no checked out .gitattributes file
  				 * there, but we might have it in the index.
  				 * We allow operation in a sparsely checked out
  				 * work tree, so read from it.
  				 */
  				res = read_attr_from_index(istate, path, macro_ok);
  		}
  	}
  
  	if (!res)
  		res = xcalloc(1, sizeof(*res));
  	return res;
  }
  
  #if DEBUG_ATTR
  static void debug_info(const char *what, struct attr_stack *elem)
  {
  	fprintf(stderr, "%s: %s\n", what, elem->origin ? elem->origin : "()");
  }
  static void debug_set(const char *what, const char *match, struct git_attr *attr, const void *v)
  {
  	const char *value = v;
  
  	if (ATTR_TRUE(value))
  		value = "set";
  	else if (ATTR_FALSE(value))
  		value = "unset";
  	else if (ATTR_UNSET(value))
  		value = "unspecified";
  
  	fprintf(stderr, "%s: %s => %s (%s)\n",
  		what, attr->name, (char *) value, match);
  }
  #define debug_push(a) debug_info("push", (a))
  #define debug_pop(a) debug_info("pop", (a))
  #else
  #define debug_push(a) do { ; } while (0)
  #define debug_pop(a) do { ; } while (0)
  #define debug_set(a,b,c,d) do { ; } while (0)
  #endif /* DEBUG_ATTR */
  
  static const char *git_etc_gitattributes(void)
  {
  	static const char *system_wide;
  	if (!system_wide)
  		system_wide = system_path(ETC_GITATTRIBUTES);
  	return system_wide;
  }
  
  static const char *get_home_gitattributes(void)
  {
  	if (!git_attributes_file)
  		git_attributes_file = xdg_config_home("attributes");
  
  	return git_attributes_file;
  }
  
  static int git_attr_system(void)
  {
  	return !git_env_bool("GIT_ATTR_NOSYSTEM", 0);
  }
  
  static GIT_PATH_FUNC(git_path_info_attributes, INFOATTRIBUTES_FILE)
  
  static void push_stack(struct attr_stack **attr_stack_p,
  		       struct attr_stack *elem, char *origin, size_t originlen)
  {
  	if (elem) {
  		elem->origin = origin;
  		if (origin)
  			elem->originlen = originlen;
  		elem->prev = *attr_stack_p;
  		*attr_stack_p = elem;
  	}
  }
  
  static void bootstrap_attr_stack(const struct index_state *istate,
  				 struct attr_stack **stack)
  {
  	struct attr_stack *e;
  
  	if (*stack)
  		return;
  
  	/* builtin frame */
  	e = read_attr_from_array(builtin_attr);
  	push_stack(stack, e, NULL, 0);
  
  	/* system-wide frame */
  	if (git_attr_system()) {
  		e = read_attr_from_file(git_etc_gitattributes(), 1);
  		push_stack(stack, e, NULL, 0);
  	}
  
  	/* home directory */
  	if (get_home_gitattributes()) {
  		e = read_attr_from_file(get_home_gitattributes(), 1);
  		push_stack(stack, e, NULL, 0);
  	}
  
  	/* root directory */
  	e = read_attr(istate, GITATTRIBUTES_FILE, 1);
  	push_stack(stack, e, xstrdup(""), 0);
  
  	/* info frame */
  	if (startup_info->have_repository)
  		e = read_attr_from_file(git_path_info_attributes(), 1);
  	else
  		e = NULL;
  	if (!e)
  		e = xcalloc(1, sizeof(struct attr_stack));
  	push_stack(stack, e, NULL, 0);
  }
  
  static void prepare_attr_stack(const struct index_state *istate,
  			       const char *path, int dirlen,
  			       struct attr_stack **stack)
  {
  	struct attr_stack *info;
  	struct strbuf pathbuf = STRBUF_INIT;
  
  	/*
  	 * At the bottom of the attribute stack is the built-in
  	 * set of attribute definitions, followed by the contents
  	 * of $(prefix)/etc/gitattributes and a file specified by
  	 * core.attributesfile.  Then, contents from
  	 * .gitattributes files from directories closer to the
  	 * root to the ones in deeper directories are pushed
  	 * to the stack.  Finally, at the very top of the stack
  	 * we always keep the contents of $GIT_DIR/info/attributes.
  	 *
  	 * When checking, we use entries from near the top of the
  	 * stack, preferring $GIT_DIR/info/attributes, then
  	 * .gitattributes in deeper directories to shallower ones,
  	 * and finally use the built-in set as the default.
  	 */
  	bootstrap_attr_stack(istate, stack);
  
  	/*
  	 * Pop the "info" one that is always at the top of the stack.
  	 */
  	info = *stack;
  	*stack = info->prev;
  
  	/*
  	 * Pop the ones from directories that are not the prefix of
  	 * the path we are checking. Break out of the loop when we see
  	 * the root one (whose origin is an empty string "") or the builtin
  	 * one (whose origin is NULL) without popping it.
  	 */
  	while ((*stack)->origin) {
  		int namelen = (*stack)->originlen;
  		struct attr_stack *elem;
  
  		elem = *stack;
  		if (namelen <= dirlen &&
  		    !strncmp(elem->origin, path, namelen) &&
  		    (!namelen || path[namelen] == '/'))
  			break;
  
  		debug_pop(elem);
  		*stack = elem->prev;
  		attr_stack_free(elem);
  	}
  
  	/*
  	 * bootstrap_attr_stack() should have added, and the
  	 * above loop should have stopped before popping, the
  	 * root element whose attr_stack->origin is set to an
  	 * empty string.
  	 */
  	assert((*stack)->origin);
  
  	strbuf_addstr(&pathbuf, (*stack)->origin);
  	/* Build up to the directory 'path' is in */
  	while (pathbuf.len < dirlen) {
  		size_t len = pathbuf.len;
  		struct attr_stack *next;
  		char *origin;
  
  		/* Skip path-separator */
  		if (len < dirlen && is_dir_sep(path[len]))
  			len++;
  		/* Find the end of the next component */
  		while (len < dirlen && !is_dir_sep(path[len]))
  			len++;
  
  		if (pathbuf.len > 0)
  			strbuf_addch(&pathbuf, '/');
  		strbuf_add(&pathbuf, path + pathbuf.len, (len - pathbuf.len));
  		strbuf_addf(&pathbuf, "/%s", GITATTRIBUTES_FILE);
  
  		next = read_attr(istate, pathbuf.buf, 0);
  
  		/* reset the pathbuf to not include "/.gitattributes" */
  		strbuf_setlen(&pathbuf, len);
  
  		origin = xstrdup(pathbuf.buf);
  		push_stack(stack, next, origin, len);
  	}
  
  	/*
  	 * Finally push the "info" one at the top of the stack.
  	 */
  	push_stack(stack, info, NULL, 0);
  
  	strbuf_release(&pathbuf);
  }
  
  static int path_matches(const char *pathname, int pathlen,
  			int basename_offset,
  			const struct pattern *pat,
  			const char *base, int baselen)
  {
  	const char *pattern = pat->pattern;
  	int prefix = pat->nowildcardlen;
  	int isdir = (pathlen && pathname[pathlen - 1] == '/');
  
  	if ((pat->flags & PATTERN_FLAG_MUSTBEDIR) && !isdir)
  		return 0;
  
  	if (pat->flags & PATTERN_FLAG_NODIR) {
  		return match_basename(pathname + basename_offset,
  				      pathlen - basename_offset - isdir,
  				      pattern, prefix,
  				      pat->patternlen, pat->flags);
  	}
  	return match_pathname(pathname, pathlen - isdir,
  			      base, baselen,
  			      pattern, prefix, pat->patternlen, pat->flags);
  }
  
  static int macroexpand_one(struct all_attrs_item *all_attrs, int nr, int rem);
  
  static int fill_one(const char *what, struct all_attrs_item *all_attrs,
  		    const struct match_attr *a, int rem)
  {
  	int i;
  
  	for (i = a->num_attr - 1; rem > 0 && i >= 0; i--) {
  		const struct git_attr *attr = a->state[i].attr;
  		const char **n = &(all_attrs[attr->attr_nr].value);
  		const char *v = a->state[i].setto;
  
  		if (*n == ATTR__UNKNOWN) {
  			debug_set(what,
  				  a->is_macro ? a->u.attr->name : a->u.pat.pattern,
  				  attr, v);
  			*n = v;
  			rem--;
  			rem = macroexpand_one(all_attrs, attr->attr_nr, rem);
  		}
  	}
  	return rem;
  }
  
  static int fill(const char *path, int pathlen, int basename_offset,
  		const struct attr_stack *stack,
  		struct all_attrs_item *all_attrs, int rem)
  {
  	for (; rem > 0 && stack; stack = stack->prev) {
  		int i;
  		const char *base = stack->origin ? stack->origin : "";
  
  		for (i = stack->num_matches - 1; 0 < rem && 0 <= i; i--) {
  			const struct match_attr *a = stack->attrs[i];
  			if (a->is_macro)
  				continue;
  			if (path_matches(path, pathlen, basename_offset,
  					 &a->u.pat, base, stack->originlen))
  				rem = fill_one("fill", all_attrs, a, rem);
  		}
  	}
  
  	return rem;
  }
  
  static int macroexpand_one(struct all_attrs_item *all_attrs, int nr, int rem)
  {
  	const struct all_attrs_item *item = &all_attrs[nr];
  
  	if (item->macro && item->value == ATTR__TRUE)
  		return fill_one("expand", all_attrs, item->macro, rem);
  	else
  		return rem;
  }
  
  /*
   * Marks the attributes which are macros based on the attribute stack.
   * This prevents having to search through the attribute stack each time
   * a macro needs to be expanded during the fill stage.
   */
  static void determine_macros(struct all_attrs_item *all_attrs,
  			     const struct attr_stack *stack)
  {
  	for (; stack; stack = stack->prev) {
  		int i;
  		for (i = stack->num_matches - 1; i >= 0; i--) {
  			const struct match_attr *ma = stack->attrs[i];
  			if (ma->is_macro) {
  				int n = ma->u.attr->attr_nr;
  				if (!all_attrs[n].macro) {
  					all_attrs[n].macro = ma;
  				}
  			}
  		}
  	}
  }
  
  /*
   * Collect attributes for path into the array pointed to by check->all_attrs.
   * If check->check_nr is non-zero, only attributes in check[] are collected.
   * Otherwise all attributes are collected.
   */
  static void collect_some_attrs(const struct index_state *istate,
  			       const char *path,
  			       struct attr_check *check)
  {
  	int pathlen, rem, dirlen;
  	const char *cp, *last_slash = NULL;
  	int basename_offset;
  
  	for (cp = path; *cp; cp++) {
  		if (*cp == '/' && cp[1])
  			last_slash = cp;
  	}
  	pathlen = cp - path;
  	if (last_slash) {
  		basename_offset = last_slash + 1 - path;
  		dirlen = last_slash - path;
  	} else {
  		basename_offset = 0;
  		dirlen = 0;
  	}
  
  	prepare_attr_stack(istate, path, dirlen, &check->stack);
  	all_attrs_init(&g_attr_hashmap, check);
  	determine_macros(check->all_attrs, check->stack);
  
  	rem = check->all_attrs_nr;
  	fill(path, pathlen, basename_offset, check->stack, check->all_attrs, rem);
  }
  
  void git_check_attr(const struct index_state *istate,
  		    const char *path,
  		    struct attr_check *check)
  {
  	int i;
  
  	collect_some_attrs(istate, path, check);
  
  	for (i = 0; i < check->nr; i++) {
  		size_t n = check->items[i].attr->attr_nr;
  		const char *value = check->all_attrs[n].value;
  		if (value == ATTR__UNKNOWN)
  			value = ATTR__UNSET;
  		check->items[i].value = value;
  	}
  }
  
  void git_all_attrs(const struct index_state *istate,
  		   const char *path, struct attr_check *check)
  {
  	int i;
  
  	attr_check_reset(check);
  	collect_some_attrs(istate, path, check);
  
  	for (i = 0; i < check->all_attrs_nr; i++) {
  		const char *name = check->all_attrs[i].attr->name;
  		const char *value = check->all_attrs[i].value;
  		struct attr_check_item *item;
  		if (value == ATTR__UNSET || value == ATTR__UNKNOWN)
  			continue;
  		item = attr_check_append(check, git_attr(name));
  		item->value = value;
  	}
  }
  
  void attr_start(void)
  {
  	pthread_mutex_init(&g_attr_hashmap.mutex, NULL);
  	pthread_mutex_init(&check_vector.mutex, NULL);
  }
  